An integrated circuit generally is fabricated on and within a substrate and includes multiple layers of materials. These multiple layers of materials can include semiconductor layers (e.g., silicon), metal layers (e.g., copper or aluminum), and insulating layers (e.g., silicon oxide or silicon nitride). An integrated circuit can also include a passivation layer for protecting underlying layers from moisture, contamination, or other conditions that can potentially degrade or damage the integrated circuit. An integrated circuit generally includes contact regions for connecting the integrated circuit to other circuits. Point contacts are generally formed in metal layers, e.g., the top level of metal.
For example, FIG. 1 shows a cross section of an integrated circuit 10 fabricated on a substrate 12. Integrated circuit 10 includes contact regions 16a, 16b and 16c (collectively 16) within a metal layer 14. Integrated circuit 10 also includes other layers of materials beneath metal layer 14. These layers of materials underneath metal layer 14 are depicted generally as other layers 13 in FIG. 1. Integrated circuit 10 is protected by a passivation layer 18.
In a post passivation interconnect (“PPI”) process, contact pads and other conductors are fabricated on top of the passivation layer 18 and connected to the contact regions 16 of the integrated circuit 10. These interconnects can be used to re-route the connections to integrated circuit 10 to facilitate contact to the package.
FIG. 2a shows a cross-section of integrated circuit 10 after a conventional PPI process, and FIG. 2b shows a top view of this same device. The PPI process has formed a connection pattern over passivation layer 18. The connection pattern includes contact pads 26a and 26b, as well as conductors 40b and 40c. After the connection pattern is fabricated, as shown in FIG. 2b, conductor 40b is connected to contact pad 26b, and conductor 40c is connected to other surrounding regions (not shown). Contact pad 26a, conductor 40b, and conductor 40c are connected, respectively, to contacts regions 40a, 40b and 40c. 